Objective To explore associations between perinatal activity and survival in infants born at 22 and 23 weeks of gestation in Sweden.
Design/Setting Data on all births at 22 and 23 weeks’ gestational age (GA) were prospectively collected in 2004–2007 (T1) or obtained from national registers in 2014–2016 (T2) and 2017–2019 (T3). Infants were assigned perinatal activity scores based on 3 key obstetric and 4 neonatal interventions.
Main outcome One-year survival and survival without major neonatal morbidities (MNM): intraventricular haemorrhage grade 3–4, cystic periventricular leucomalacia, surgical necrotising enterocolitis, retinopathy of prematurity stage 3–5 or severe bronchopulmonary dysplasia. The association of GA-specific perinatal activity score and 1-year survival was also determined.
Results 977 infants (567 live births and 410 stillbirths) were included: 323 born in T1, 347 in T2 and 307 in T3. Among live-born infants, survival at 22 weeks was 5/49 (10%) in T1 and rose significantly to 29/74 (39%) in T2 and 31/80 (39%) in T3. Survival was not significantly different between epochs at 23 weeks (53%, 61% and 67%). Among survivors, the proportions without MNM in T1, T2 and T3 were 20%, 17% and 19% for 22 weeks and 17%, 25% and 25% for 23 weeks’ infants (p>0.05 for all comparisons). Each 5-point increment in GA-specific perinatal activity score increased the odds for survival in first 12 hours of life (adjusted OR (aOR) 1.4; 95% CI 1.3 to 1.6) in addition to 1-year survival (aOR 1.2; 95% CI 1.1 to 1.3), and among live-born infants it was associated with increased survival without MNM (aOR 1.3; 95% CI 1.1 to 1.4).
Conclusion Increased perinatal activity was associated with reduced mortality and increased chances of survival without MNM in infants born at 22 and 23 weeks of GA.
Data availability statement
Data are available on reasonable request.
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Contributors KK (2004–2007), AF,SH and MN (2014–2016 and 2017–2019) had full access to all data in the study and took responsibility for the integrity of the data. All authors conceived of the study idea. AF, SH and MN drafted the manuscript. AF, KK, FS, MD, MN and LB performed the statistical analyses. All authors were responsible for acquiring, analysing and interpreting data. All authors critically revised the manuscript and approved the final version of the manuscript. AF had full access to the data in the study. AF is guarantor.
Funding MN was supported by a grant from a regional agreement on clinical research (ALF) between Region Stockholm and Karolinska Institute (2020-0443) and by the Childhood Foundation of the Swedish Order of Freemasons. The Swedish Neonatal Quality Register was funded by the Swedish Government (Ministry of Health and Social Affairs) and the body of Regional Health Care Providers.
Disclaimer The funders had no role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript and decision to submit the manuscript for publication.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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